1. Field of the Invention
The present invention relates to an apparatus for transferring a circuit component such as an electric-circuit component or an electronic-circuit component, and particularly to the art of changing the height position of a circuit-component holder of the apparatus.
2. Related Art Statement
Japanese Patent Application laid open for inspection under Publication No. 5(1993)-196110 discloses a circuit-component ("CC") transferring device which includes a component holder for holding a CC, and a movable member for moving the component holder holding the CC, and which changes the height position of the component holder while the movable member moves the same. The CC transferring device is employed as a CC mounting device in a CC mounting system. The known CC mounting device includes a plurality of component holders and an intermittently rotatable body which is rotatable about a vertical axis line, which supports the component holders such that the component holders are equiangularly spaced from each other about the vertical axis line, at a predetermined regularly-spacing angle, and which is intermittently rotatable in such a manner that the rotatable body is continuously rotated by a predetermined intermittent-rotation angle in a first step and then is stopped in a second step and the first and second steps are repeated, the predetermined intermittent-rotation angle being equal to the predetermined regularly-spacing angle. The rotatable body has a plurality of through-holes in which a plurality of pairs of vertically movable straight rods are fitted, respectively, such that each pair of rods are movable in a direction parallel to the vertical axis line of the rotatable body. The number of the pairs of straight rods is equal to the number of the component holders. The respective upper end portions of the two straight rods of each pair which project upward from the rotatable body are connected by a connection member to which a roller as a cam follower is attached such that the roller is rotatable about a horizontal axis line thereof perpendicular to the vertical axis line of the rotatable body. The roller is rotatably fitted in an annular cam groove which is formed in an outer circumferential surface of a stationary, cylindrical cam member. The annular cam groove includes two height-changing portions the height position of each of which continuously changes in the circumferential direction of the cylindrical cam member.
A holding member, fixed to respective lower end portions of the two straight rods of each pair, holds one component holder such that the component holder is movable in an axial direction thereof and is rotatable about an axis line thereof. Thus, when the rotatable body is rotated about the vertical axis line thereof, all the component holders are revolved around the vertical axis line. Simultaneously, as the roller corresponding to each component holder is moved in each of the height-changing portions of the annular cam groove, each component holder is moved downward or upward. The roller is attached to the connection member connecting the two straight rods of each pair, such that the roller is not rotated about a vertical axis line and is always held in engagement with the cam groove.
The known CC mounting device receives, from a CC supplying device of the CC mounting system, CCs at a component receiving position corresponding to the highest portion of the annular cam groove, and mounts the CCs, on a circuit substrate ("CS") supported by a CS supporting device of the CC mounting system, at a component mounting position corresponding to the lowest portion of the annular cam groove. The CS supporting device is provided below the CC supplying device. Thus, the CS supporting device can be moved, while supporting the CS, to a desired position in a horizontal plane, so that each of predetermined CC mounting places on the CS can be positioned right below the component mounting position where the CC is mounted at each CC mounting place on the CS. Since the CS supporting device is movable in a space below the CC supplying device, the CC mounting device or the CC mounting system can be produced in small size. In addition, the diameter of the rotatable body can be reduced, which contributes to increasing the speed of rotation of the rotatable body and thereby improving the efficiency of mounting of CCs on CS.
However, the known CC mounting device employs the groove cam and the rollers as the cam member and the cam followers, respectively, and accordingly requires that the rollers be held in engagement with the groove cam. To this end, support shafts by which those rollers are rotatably supported, and vertically movable members (each of which consists of a pair of vertically movable straight rods, a connection member, a holding member, etc.) each of which is vertically movable while supporting a corresponding one of the support shafts, must be held by the rotatable body such that none of the support shafts and the vertically movable members are rotatable relative to the rotatable body. This leads to increasing the size of the rotatable body, the total number of parts needed, and the secondary angular moment, and the production cost of the CC mounting device.